The present invention relates to an endoscope having a protective cover that prevents a flexible inserting tube from being sharply bent in a vicinity of an end thereof connected to an operation unit.
A flexible inserting tube of an endoscope is connected, at a proximal end thereof, to an operation unit that is manipulated to control the bending of a bendable portion of the flexible inserting tube. Since the operation unit has a rigid body, buckling of optical fibers arranged within the flexible inserting tube is likely to occur if the flexible tube is sharply bent near the proximal end thereof connected to the operation unit. Therefore, some endoscopes are provided with an elastic protective cover that is connected to the operation unit so as to surround a proximal end portion of the flexible inserting tube and thereby prevent the flexible inserting tube from being bent sharply near the end connected to the operation unit.
The protective cover is a hollow cylinder having a tapered wall of which thickness increases toward the operation unit. Thus, the outer diameter of the protective cover is significantly larger at an proximal end thereof than at an distal end. Generally, such a configuration of the protective cover is suitable for an endoscope, specifically if the flexible inserting tube is much narrower compared to the operating unit, since a large step will not be formed between the flexible inserting tube and the operation unit.
Endoscopes provided with a disposal cover sheath are known. The cover sheath detachably covers the flexible inserting tube in order to prevent pollution of the flexible inserting tube during endoscopic inspections. The size of the cover sheath is adjusted to the size of the flexible inserting tube. A coupling ring is provided to the proximal end of the cover sheath. The flexible inserting tube is inserted into the cover sheath through the coupling ring until the coupling ring can be fixed to the operation unit.
The endoscope utilized together with the disposal cover sheath, however, cannot adopt the protective cover since the protective cover, of which the outer diameter considerably increases toward the proximal end thereof, inhibits the coupling ring to be moved to the operation unit and coupled thereto. Therefore, the flexible inserting tube of the endoscope provided with the cover sheath may easily bend near the end connected to the operation unit and causes buckling of the optical fibers arranged therein.
Therefore, there is a need for an endoscope provided with a protective cover that prevents sharp bending of a flexible inserting tube near the end thereof connected to an operation unit without inhibiting a coupling ring of a cover sheath to be coupled to the operation unit.
The present invention is advantageous in that an endoscope is provided that satisfies the above-mentioned need.
According to an aspect of the invention an endoscope is provided that includes a flexible inserting tube to be inserted into a body cavity, an operation unit connected to a proximal end of the flexible inserting tube for operating the flexible inserting tube, and an hollow cylindrical cover member connected to the operation unit to surround a portion of the flexible inserting tube near the proximal end thereof. A proximal end portion of the cover member is made of a first material while a distal end portion thereof is made of a second material. The first material has higher stiffness than the second material.
The endoscope arranged as above does not require significant increase of the wall thickness or the outer diameter of the cover member toward the proximal end thereof to get higher stiffness at the proximal end portion than at the distal end portion thereof. Thus, the cover member can be formed so as to have an outer diameter smaller than an inner diameter of a coupling ring of a cover sheath.
In an exemplary embodiment, the cover member includes a first member and a second member connected to a distal end of the first member. The cover member is connected to the operation unit at a proximal end of the first member. The first member is made of a material having higher resiliency than a material of the second member.
In the above case, each of the first and second members may have a tapered end, and connected to each other at the tapered ends thereof so that the stiffness gradually varies at a junction of the first and second members.
In another exemplary embodiment, the cover member includes a base cylinder and a stiffness adjusting cylinder. The base cylinder has a proximal side portion and a distal side portion having smaller outer diameter than the proximal side portion. The stiffness adjusting cylinder has lower stiffness than the base cylinder and is mounted on the distal side portion of the base cylinder. In this case, the thickness of the stiffness adjusting cylinder may be substantially equal to a half of an outer diameter difference between the proximal and distal side portions of the base cylinder, so that the outer diameter of the cover member becomes constant over the length thereof.
In still another embodiment, the cover member includes first, second, and third cylindrical members connected to each other in this turn, and the cover member is connected to the operation unit at a proximal end of the first cylindrical member. In this case, the first, second and third cylindrical members are arranged to have, respectively, highest, intermediate and lowest stiffness thereamong so that the stiffness of the cover member decreases from the proximal end toward the distal end thereof.
In still another embodiment, the cover member is made from a mixture of a first material and a second material having lower stiffness than the first material, and the rate of the first material in the mixture is decreased from a proximal end of the cover member toward a distal end thereof. In this case, the cover member may be further tapered such that wall thickness of the cover member decreases toward the distal end thereof.
According to another aspect of the invention, a protective cover to be connected to an operation unit of an endoscope for surrounding a flexible inserting tube connected at a proximal end thereof to the operation unit is provided. The cover member includes a hollow cylindrical body having a proximal end, a distal end, a proximal end portion defined in a vicinity of the proximal end, and a distal end portion defined in a vicinity of the distal end. The proximal end is formed to be connectable to the operation unit. The proximal and distal end portions are made of first and second materials, respectively. The first material has higher stiffness than the second material.